make legacy fails

[jbirky]

When running make legacy there is the following error with declared variables in POISE:

gcc -o bin/vplanet src/*.c -lm -DGITVERSION=\"v1.0.0-1643-gc2fd79de8915981786f11adaec39f9965517a557\"
src/poise.c: In function ‘fvPoiseSeasonalInitialize’:
src/poise.c:6792:3: error: ‘for’ loop initial declarations are only allowed in C99 mode
   for (int iLat = 0; iLat < body[iBody].iNumLats; iLat++) {
   ^
src/poise.c:6792:3: note: use option -std=c99 or -std=gnu99 to compile your code
src/poise.c: In function ‘fvFluxesByLatitude’:
src/poise.c:6886:2: error: ‘for’ loop initial declarations are only allowed in C99 mode
  for (int iLat = 0; iLat < body[iBody].iNumLats; iLat++) {
  ^
src/poise.c:6902:5: error: ‘for’ loop initial declarations are only allowed in C99 mode
     for (int jLat = 0; jLat < body[iBody].iNumLats; jLat++) {
     ^
src/poise.c: In function ‘fvCalculateSeaIce’:
src/poise.c:7074:3: error: ‘for’ loop initial declarations are only allowed in C99 mode
   for (int iLat = 0; iLat < body[iBody].iNumLats; iLat++) {
   ^
make: [legacy] Error 1 (ignored)

this apparently happens on machines where the standard is not set to C99. Either this issue should be fixed in POISE or the makefile should specify std

-gcc -o bin/vplanet src/*.c -std=c99 -lm -DGITVERSION=\"$(GITVERSION)\"